Spark plug and mounting therefor



Patented Mar.

v OFFICE scam; PLUG AND MOUNTING macros Francis John Orzel, Flushing, N. Y. Application March 20, 1944, Serial No. senses 9 Claims.

This invention relates generally to spark: plugs and the mounting thereof particularly in internal combustion engines for aeroplanes.

The ordinary spark plug as usually mounted in aeroplane engines is very difilcult to remove for inspection, replacement or other purpose desired, after it is used.

The innermost threaded portion of such plugs usually protrudes into the piston cylinder exposing its lowermost threads to the terrific heat generated in such cylinder. In time such threads become chipped and deiormedor otherwise damaged by such heat no matter what the material with which the plug is formed. Furthermore the gases and products of combustion penetrate beyond the thread joints and pass outwardly be tween the outer threaded surface of the plug and the inner threaded surface of its bushing iniuring said threads and clogging up the space between the threads. When the threads are in this condition, it is very dimcult to remove the plug from its bushing.

It is one of the objects of my invention to shield the threaded portion of the plug from such terrific heat.

Another object is to prevent the gases and products of combustion from passing along the plug.

A further object isto prevent preignitlon of the mixture.

Another object is to keep the heating of the plug to a minimum.

Another object is to provide a spark plug and bushing therefor for aeroplane engines wherein the spark plug is readily removed for inspection or replacement after use.

- Another object is to provide a spark plug construction that is simple and inexmnsive and posiitve in action.

I accomplish the foregoing and other objects and advantages by providing a spark plug having a metallic shell or body with a threaded stem portion terminating in a spherical or ball-shaped end and combining therewith a. bushing member having a rounded annular member adapted to engage the rounded end of the plug for providing a gas tight juncture at such point of engagement.

The invention will be better understood from the description thereof to follow taken in connection with the accompanying drawing showing a sectional view of a fragment of a casing of an internal combustion engine for an aeroplane with my improved spark plug and its bushing shown in section in operative position.

The engine casing is provided with the usual opening 5 above the piston cylinder for receiving the bushing member l, in threaded engagement therewith. The bushing is provided with the usual internal screw threads. The bottom or inner end of the bushing however is formed with an integral bulbous or rounded annular flange portion 8.

My improved spark plug comprises a shell or body portion formed of metal, with an outer grooves stem portion to and a central flange portion I! for receiving a tool for manipulating the plug. Only a portion or the outer grooved portion is shown.

An inner threaded stem portion i2 is provided and this portion terminates in a rounded or ball shaped end it formed with a plurality of openings it to permit the entrance of the mixture. The threads on the inner stem portion 5 2 end at a point remote from its rounded end leaving a space it between the bushing and plug. This space traps air which counteracts the internal pressure of the cylinder against leakage.

When the spark plug is screwed into its hushing to operative position as shown in the drawing. the surface of the rounded or ball-shaped end it engages the rounded surface of the annular fiance 9 and torms a gas tight juncture at this point of attachment as indicatedat E6.

The bulbous annular flange s forms a shield preventing any gases or other products from passing therebeyond and absorbs the excessive heat keeping the heating of the plug beyond said flange down to a minimum.

It will be noted that the innermost threads at the plug are remote from the annular flange 9 and out of the danger zone.

The external threads on the inner stem portion 12 could however be formed all the way inward to the annular flange 9 and said flange could be formed with a. suitable surface to coact with the innermost thread, ii. desired and that a lubricant such as graphite grease is ordinarily applied to the threads.

It will also be understood that a gasket member may be interposed between the engaging portions of the plug and bushing flange 9 if desired.

From "the foregoing it will be seen that I have designed a. spark plug and bushing therefor which are especially adapted for high tension work such as is found in aeroplane engines. The thread portions of the plug and bushing are protected from injurious gases and the like and will remain in perfect condition permitting the plug to be readily unscrewed when desired for any purpose.

Changes in details of the plug and bushing might be made without departing from theprlnoiple of the invention and I desire to be limited only by the state of the prior art and the oppended claims.

I claim:

1. A threaded spark plug and threaded bushing therefor and meens for shielding the threaded portions from gases including a line to line contact between the plug and bushing.

2. A threaded spark plug and threaded bushing therefor, said plug and bushing having cooperating annular portions with line to line contact for. shielding the threaded portions from gases.

3. A threaded spark plug and threaded bushing therefor, said plug and bushing having cooperating annular portions with line to line oontact forming an annular trap for preventing gases from penetrating to the threads of said lug and I:

a spherical perforated end portion and a bulbous nsozeor annular flange on one end oi said bushing adepted to coact with the spherical end of said plug for preventing gases from penetrating to the threaded portions of the plug and bushing.

"I. In an aeroplane internal combustion engine, a spark plug having a threaded stem portion with an end portion having a spherical periphery, a. bushing for said plug having a bulbous annular flange portion adapted to engage the spherical periphery of said plug for forming a seal to prevent gases from passing beyond said point of engagement.

8. A bushing for a spark plug comprising a tubular threaded body portion. and an integral bulboius annular flange on one end of said body port on. v

9. In an aeroplane internal combustion e a spark plug having a body portion with external threads along a portion of said body end with an end portion having a sphoricolperiphery, a bushing for said plug having a bulbous annular flange portion adapted to engage the spherical periphery of said plug at a point remote from. the threaded portion of the plug body forming an air space between said plug body and said annular flange for trapping air in said space to counteract the pressure in the cylinder.

' more zomv 032m. 

